In the near future second-generation (2G) mobile networks will be complemented and partly replaced with third generation (3G) mobile networks. In many parts of the world this will mean a transition from a situation where the 2G standard is the only dominant mobile network technology to a situation where there are two dominant mobile network technologies: 2G and 3G. In Europe, for example, there will be a switch from GSM being the sole dominant standard to GSM and 3GPP (3rd Generation Partnership Project) both being dominant standards.
Thus a network operator will in the future have often a mobile network containing GSM and 3GPP technology, where the 3GPP technology may be deployed using several 5 MHz 3GPP carriers. Also the cell sizes in both standards may differ from indoor and street level pico-cells and micro-cells to large macro-cells. It will then be necessary for the operator to have to decide how to serve the required traffic using the different network technologies and cell types available thereto.
The operator's goal is to maximise the number of users served and to provide some predefined coverage probability in the coverage area. The required traffic in the coverage area will consist of various connections where different quality of service (QOS) requirements are desired. QOS may be defined by, for example, bit rate, maximum allowed delay and bit error rate (BER). To maximise the number of users served, the different type of connections must be served in such a cell type and with such technology where it is possible and where it requires the least effort.
For example, consider a user equipment (UE) requesting a real-time connection at a bit rate 384 kbit/s. The operator may primarily want to serve this user with a 3GPP cell, because the 3GPP standard can provide 384 kbit/s bit rate.
In current proposed systems the operator would have to rely on cell selection or handover algorithms provided by the vendor, which might not result in satisfactory distribution of different type of connections in the available technologies and cell types from the operators point of view.
In the second-generation systems e.g. GSM and IS-95, the problem of dividing required traffic to cells with different technology and type based on the service type is not important for two reasons. Firstly, in second generation systems the required traffic consists mostly of speech services. Data services are also possible but are less used than speech. The variety in the offered traffic in terms of bit rates, maximum delay and BER requirements is significantly smaller than in 3GPP networks. Secondly, prior to the deployment of 3GPP networks it has not been common for an operator to operate a network consisting of systems from several standards, where intersystem handovers would be possible.
It is an aim of the present invention to provide an improved technique for selecting a target cell in a wireless communication system supporting more than one communication standard.